Sonic screwdriver. The real beauty is the perception of the sonic device. It's as big as a pen. It makes a sound, and although the full set of features is never listed, it opens or closes all locks: mechanic or electronic. Only not deadbolt locks. But it does seem to be able to fix, mend or sabotage a fair selection of different appliances; both of what we have today and in the future. And to top all that, it can also serve as a weapon.

The Doctor usually is accompanied by a contemporary human. Who is of course as impressed with the device as the viewers at home are. This device is impressive bordering the absurd. "What _can't_ it do??" we wonder.

And then, just as you've settled for the concept of a device sooooo darn powerful, an alien brings you back to reality when they say with utter disdain: "It's _just_ a screwdriver"

Ah, I may be a bit of a sucker, but I love the contrast therein.

Still, between a lightsaber and a sonic screwdriver, I'd choose the screwdriver and good running shoes any day of the week.

EDIT: [GOD_MODE]Any and all doom weapons with maximum ammo and perfect health, I still take the shotgun.[/GOD_MODE]